Spirobifluorene derivatives, their preparation and uses thereof

ABSTRACT

The invention concerns Spirobifluorene derivatives having the general formula (II) and the corresponding, radical anions that can be represented via the general formula (II):  
                 
in which K, L, M and N, the same or different from each other, are independently: H or A-C═O, with the proviso that it is never K=L=M=N═H, wherein A is an aromatic group, possibly substituted with at least an R′ group selected in the group of the substituents commonly used in organic chemistry and/or at least one R group where R=aliphatic radical. The invention also concerns the method for preparing said derivatives and radical anions. Said compounds are applied in the field of components for molecular electronics, in particular systems for electroluminescence, molecular-based computational systems, OLEDs, molecular switching components, components for non-linear optics, field-effect transistors and semiconductors with negative differential resistance.

FIELD OF THE INVENTION

The present invention concerns derivatives of Spirobifluorene,hereinafter also called SBF, having general formula (II), the method forpreparing said compounds and uses thereof, in particular their use inthe field of molecular electronics.

PRIOR ART

Spirobifluorenes are a class of spiro-compounds well-known in organicchemistry [(9,9′-Spirobi[9H-fluorene])] and are generally characterisedby the following formula (I):

Their preparation is described by Prelog (1) and their applications aredescribed in Aviram (2).

The SBFs are a class of organic molecules that can be used instead oftheir corresponding inorganic species in the arrangement and productionof electronic circuits and switches.

The patent U.S. Pat. No. 5.840.217 describes derivatives of SBF for useas materials for electroluminescence.

The inventors have now found a class of compounds, derivatives of SBF,with particularly interesting chemical-physical characteristics for usein the field of molecular electronics. The general term molecularelectronics refers to the technical field in which organic molecularspecies can be used for electronic applications (3), comprising thetechniques of electroluminescence and photoluminescence.

SUMMARY OF THE INVENTION

Objects of the present invention are derivatives of SBF, in particularthe benzoyl derivatives having the following general formula (II):

in which K, L, M and N, the same or different from each other, areindependently:

H or A-C═O (in the following indicated as A-C═O), with the proviso thatit is never K=L=M=N═H, wherein A is an aromatic group, possiblysubstituted with at least an R′ group selected in the group of thesubstituents commonly used in organic chemistry and/or at least one Rgroup where R=aliphatic radical.

Another object of the invention are the enantiomers corresponding to thecompounds of formula (II).

Another object of the invention are the radical anions corresponding tothe compounds of formula (II). Radical anion is the chemical speciesobtained by the addition of an electron to the corresponding neutralspecies.

A further object of the invention is the method for preparing thecompounds of formula (II) and the method for preparing the correspondingradical anions.

Yet another object of the invention are the electronic devices, inparticular the molecular-based computational systems, the OLEDs (OrganicLight Emitting Diodes) and the components for non-linear optics that usethe compounds of formula (II) or the corresponding radical anions.

A further object of the invention is the use of the derivatives of SBFand the corresponding radical anions in components for molecularelectronics, in particular for the molecular-based computationalsystems, for the OLEDs and for non-linear optics.

Further objects will become evident from the detailed description of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

The present invention refers to the derivatives of SBF of formula (II),i.e. spiro compounds in which at least one substituent is A-C═O, Aindicating an aromatic group or a substituted aromatic group, possiblycondensed, possibly containing heteroatoms, possibly bearing at leastone radical R, with R═H or aliphatic group. Preferably A is an aromaticradical substituted by at least one member selected from the group ofhalogens, alkyl radical, preferably C₁₋₆(alkyl), trifluoromethyl,hydroxyl, —SH, —SC(C₁₋₆ alkyl), alkoxy, nitro, cyano, —COOH, —COOC(C₁₋₄alkyl), —NH₂, —NC(C₁₋₄alkyl)₂, benzyl, benzoyl.

Preferably the A group bears one or more R and/or R′ substituents,wherein R is selected in the group of: linear, branched and cyclicaliphatic C_(1-n), with n positive integer≧0, preferably C₁₋₁₈(alkyl),more preferably C₁₋₆(alkyl); and R′ is selected in the group of:halogens, trifluoromethyl, hydroxyl, —SH, —SC[C₁₆(alkyl)], alkoxy,nitro, cyano, —COOH, —COOC[C₁₋₄(alkyl)], —NH₂, —NC[C₁₄(alkyl)]₂, benzyl,benzoyl.

According to a preferred embodiment A can be selected in the group ofthe following derivatives: phenyl, biphenyl, 1-naphthyl, 2-naphthyl,2-thienyl, 2-furyl, 2-pyrrolyl, 3-thienyl, 3-furyl, 3-pyrrolyl,9-anthryl, biphenylenyl, perylenyl, fullerenyl, and correspondingderivatives, said derivatives being preferably substituted by at leastone R group and/or an R′ group, wherein R and R′ have the meaning aboveindicated.

Within the scope of the present invention, and with reference to formula(II), the following compounds are particularly preferred:

-   -   the compounds of formula (III):        wherein A has the meaning in the above and R₁═R₂═R₃═H; or        R₁═R₃═H and R₂═C₁₋₆(alkyl); or R₁═R₂═H and R₃═C₁₋₆(alkyl); or        R₂═H and R₁═R₃═C₁₋₆(alkyl);    -   the compounds of formula (IV):        wherein R₅=A-C═O with A is as in the above and R₄═R₆═H; or        R₅=A-C═O and R₄═R₆═C₁₋₄(alkyl); or R₆=A-C═O and R₄═R₅═H; or        R₆=A-C═O and R₄═R₅═C₁₋₄(alkyl);    -   the compounds of formula (V):        wherein R₇═R₉=A-C═O and A is as in the above and R₈═H; or        R₇═R₉=A-C═O and R₈═C₁₋₄(alkyl);    -   the compounds of formula (VI):        wherein R₁₀═R₁₁═R₁₂=A-C═O with A as in the above.        the compounds (VII) wherein L=M=N═H and K=A-C═O in position 2,        with A=phenyl and R═H;    -   the compounds (VIIIa) wherein L=N═H, K and M in position 2 and        2′ are A-C═O, with A=phenyl and R═H;    -   the compounds (VIIIb) wherein L=M=H, K and N in position 2 and        7′ are A-C═O, with A=phenyl and R═H;    -   the compounds (IX) wherein L=M=N═H, K in position 2 is A-C═O,        with A=phenyl and R=p-tert-Bu;    -   the compounds (Xa) wherein L=N═H, K and M in position 2 and 2′        are A-C═O, with A=phenyl and R=p-tert-Bu;    -   the compounds (Xb) wherein is: L=M=H, K and N in position 2 and        7′ are A-C═O, with A=phenyl and R=p-tert-Bu;

As some of the molecules of the invention have an axial asymmetry, thecorresponding enantiomers fall within the scope of the invention, eitherin mixtures or as pure compounds.

The presence of the aliphatic R group on the A group, for example thetert-Bu group as in the molecules (IX) and (Xa and Xb), has theadvantage of improving solubility in the common solvents, e.g.acetonitrile, dimethylformamide, CDCl₃ and other solvents, thereforeimproving processability and identification by means of the usualspectroscopic analytical techniques.

The COCl intermediates needed for the preparation of the compounds offormula (II) are in most cases commercially available compounds or knowncompounds, either directly or in the form of the corresponding COOHderivatives. It is common practice to obtain the COCl derivativestarting from the corresponding COOH derivative. With particular regardto the fullerenyl derivative, it can be prepared starting from thefullerene compound C60H, ([5,6]Fulleren-C60-lh-1 (2H)-yl), RegistryNumber: 143631-66-7.

The derivatives of the compounds of formula (II) can be preparedaccording to the standards techniques commonly used in organicchemistry.

A method for preparing the compounds of the invention is based on theuse as starting product of the non-functionalised SBF (formula (I)). Themethod involves the following stages: addition, by means of standardmethods (e.g. described in (4)), of A-C═OCl, with A having theabove-mentioned meaning, to the non-functionalised SBF (formula (I)).Optimal conditions for obtaining the required compounds are within thecapabilities of any technician in the field. A general preparation isgiven in the following in the experimental part.

An alternative method for preparing the compounds of the invention isbased on the use, as intermediate, of SBF functionalised as acidchloride SBF(COCl)_(x), with x positive integer≧1 and equal to thenumber of substituents to be obtained on the SBF. The acid chloride isthen combined with A-H, in which A has the above-mentioned meaning. Theintermediate acid chloride can be prepared from the correspondingcarboxylic acids of the SBF, SBF(COOH)_(x), in turn obtained from thecorresponding acetyl derivatives SBF(COCH₃)_(x), x having in both casesthe above-mentioned meaning.

The compound 9,9′-Spirobi[9H-fluorene]-2,2′-dicarbonyl dichloride(SBF(COCl)₂) is known by Registry Number 67665-11-6.

The compounds 9,9′-Spirobi[9H-fluorene]-2-carbonyl chloride,9,9′-Spirobi[9H-fluorene]-2,2′,7-tricarbonyl trichloride and9,9′-Spirobi[9H-fluorene]-2,2′,7-7′tetracarbonyl tetrachloride are new;they can be prepared like the dichloride mentioned above, thepreparation of which is illustrated in the examples.

The radical anions of the compounds (II) are obtained preferably viachemical and electrochemical route by the addition of an electron to thecorresponding neutral compound; the electrochemical method isparticularly preferred as it is easy to perform.

The radical anions of the compounds (VII), (VIIIa, VIIIb), (IX) and (Xa,Xb) are particularly preferred. The electrochemical method for obtainingthe radical anions in general is described in (5).

This method is performed using an electrochemical cell comprising twocompartments: one anodic and one cathodic; the cathodic compartmentcontains a working electrode and a calomel reference electrode. Anaprotic solvent is made anhydrous by means of usual procedures (5); asupporting electrolyte is added to it, also made anhydrous, in order toobtain a concentration between 1 M and 0.01 M, preferably 0.2 M and 0.05M, particularly preferably approximately 0.1 M. A general preparation isgiven in the following in the experimental part.

The electrolytic solution prepared as described is placed in the anodiccompartment that is separated from the cathodic compartment by a portionof the same electrolytic solution appropriately gelled and containingthe anode (Pt network). The compound in question is added, undernitrogen, to the cathodic compartment, containing another portion of thesame electrolytic solution, in order to obtain concentrations between0.1 M and 0.1 mM, preferably in the range between 0.01 M and 0.5 mM,particularly preferably approximately 1 mM. An appropriate d.d.p. isapplied between the electrodes in order to obtain the required radicalanion.

The materials that can be used to build the working electrode arepreferably platinum, mercury, lead, silver, composite materials based onTi, conducting carbon materials, conducting materials containing carbon,vitreous carbon, chemically modified electrodes; vitreous carbon isparticularly preferred due to the following characteristics: largeapplicable d.d.p. window, economic, non-toxic and easy to use. Thesolvents that can be used are preferably aprotic solvents and theirmixtures, for example: acetonitrile, dimethylformamide,N-methylpyrrolidone, dimethylsulfoxide; dimethylformamide isparticularly preferred.

The supporting electrolytes that can be used are those preferablycontaining: perchlorate anions, tetrafluoborate anions,hexafluophosphate anions, lithium cations, sodium cations,tetraalkylammonium cations and related mixtures; the perchlorate anionsand tetraethylammonium cations are particularly preferred.

The working temperatures can be between −20° C. and +50° C.; roomtemperature is particularly preferred.

Due to the presence of the C═O group between the SBF and the A group,the compounds of the invention form the radical anions more easily thancorresponding compounds in which the C═O is absent.

In fact it has been observed that the insertion of the C═O functionalgroup results in a considerable improvement of the property of themolecule as it increases its “electron-acceptor” characteristics,shifting the standard potential, E°, of the molecule towards morepositive (lower) values. It is known that the standard potential, E°,defined as in (6), shifts towards more positive values with respect to areference molecule when its properties as electron-acceptor are improvedwith respect to the reference molecule.

With reference to the derivatives of Spirobifluorene with generalformula (II) according to the present invention and the correspondingradical anions, the standard potential E° shifts towards more positivevalues of the quantity ΔE°.

The advantage of the increase of ΔE° towards more positive potentialswith respect to the values of corresponding compounds not containing thefunctional group C═O is the following: uses of the molecules of theinvention involve energy saving with respect to the former. The ΔE°measured by means of cyclic voltammetry (5) for addition of thesubstituent R—Ar—C═O according to the invention, with respect to themolecule of the SBF (formula (I)), can be quantified roughly as follows:ΔE° min 700 mV, for example 860 mV for the compound (mixture of Xa andXb).

The compounds of the invention and the corresponding radical anions canbe advantageously used in the field of electroluminescence in general,in particular light emitting diodes (OLEDs); as components of molecularswitching; for non-linear optics; in molecular-based computationalsystems (the latter described in Aviram, ref. (1)); in field-effecttransistors (FET) (7) and in semiconductors with negative differentialresistance (NDR).

The compounds according to the invention can be applied in the form ofthin films or coating on a suitable substrate according to techniquesknown to experts in the field. The devices have at least one activelayer comprising the compounds of the invention, applied on saidsubstrate.

The following examples are provided to illustrate the invention andshould not be considered as restrictive of the scope thereof.

EXAMPLES

Reagents and instruments: carbon sulphide (CS₂), dichloromethane(CH₂Cl₂) Carlo Erba; aluminium trichloride (AlCl₃ Fluka); benzoylchloride (PhCOCl) Aldrich; tert-Bu-benzoyl chloride Aldrich; acetylchloride (MeCOCl) Fluka; thionyl chloride (SOCl₂) Merck; tert-butylbenzene (t-BuBz) Lancaster; IR: Perkin-Elmer 298, Shimadzu 470; NMR:Bruker AC 200.

All carbonyl compounds (4-(nitro)benzoyl chloride, 2-furoyl carbonylchloride, 4-(fluoro)benzoyl chloride, 4-(methoxy)benzoyl chloride,pentafluorobenzoyl chloride, 2-thienyl carbonyl chloride) were fromLancaster Synthesis Ltd.

Example 1 General Preparation of Mono Derivatives

Acid chloride (1.90 mmol) is dissolved in 20 ml of dichloromethane,cooling to 15° C. under stirring, then added with 274 mg of anhydrousAlCl₃ (2.05 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluanthexane:CHCl₃, to obtain the mono substituted derivative (yields from 30to 80%).

Example 2 General Preparation of di-derivatives

Acid chloride (3.48 mmol) is dissolved in 20 ml of dichloromethane,cooling to 15° C. under stirring, then added with 695 mg of anhydrousAlCl₃ (5.21 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CHCl₃, to obtain the di substituted derivative (yields from 70 to 90%).

Example 3 Preparation of the monobenzoyl derivative SBFCOPh (VII).

0.9 g of benzoyl chloride (6.32 mmol) are dissolved in 20 ml ofdichloromethane, cooling to 15° C., under stirring, then adding 2.95 gof finely powdered anhydrous AlCl₃ (22.12 mmol). 1.0 g of9,9′-spirobifluorene (I) (3.16 mmol) dissolved in 10 ml ofdichloromethane are then added drop wise under stirring for 10 min. Thereaction mixture is brought to room temperature and the mixture is thenrefluxed for one hour. 50 g of ice and 25 ml of a 2N solution of HCl areadded to the residue. The water phase is extracted with CH₂Cl₂ (3×15ml).

The combined organic phases are washed with water (20 ml), dried andconcentrated until 1.8 g of solid residue are obtained. The product ispurified by means of silica gel chromatography with eluant hexane:CH₂Cl₂70:30 until 1.2 g (90%) of 2-benzoyl-9,9′-spirobifluorene (VII) areobtained; melting point 260-261° C.

2-benzoyl-9,9′-spirobifluorene (VII) (C32 H20 O):

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 8.15-6.75 (20 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 196.05 (C═O); 149.11, 148.39,146.17 140.54, 137.91, 136.91, (all quaternary carbons); 132.13, 131.14,130.17, 129.84, 129.22, 128.46, 128.27, 128.25, 128.13, 125.56, 124.19,121.12, 119.64 (all CH); 65.89 (C-spiro); ESI-MS (negative mode): 457.4(M+H⁺+2H₂O);

IR (CCl₄, cm⁻¹): 1696 (C═O).

Example 4 Preparation of 2-(p-nitro)-benzoyl-9,9′-spirobifluorene

352 mg of 4-(nitro)benzoyl chloride (1.90 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with274 mg of anhydrous AlCl₃ (2.05 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CH₂Cl₂ 70:30, to obtain 310 mg of2-(p-nitro)-benzoyl-9,9′-spirobifluorene (C32H19NO3; MW=465.51; yieldsof 42%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.75-8.20 (19 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 194.00 (C═O), 150.14, 149.64,149.59, 147.52, 147.06, 143.21, 141.86, 140.05, 135.44 (all quaternarycarbons), 130.79, 130.67, 130.42, 129.52, 128.10, 127.92, 125.69,124.34, 123.80, 123.33, 121.07, 120.27, 119.82 (all CH), 65.91(C-spiro).

IR (CCl₄, cm⁻¹): 1664 (C═O).

Example 5 Preparation of 2-furoyl-9,9′-spirobifluorene

454 mg of 2-furoyl carbonyl chloride (1.90 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with274 mg of anhydrous AlCl₃ (2.05 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CH₂Cl₂ 70:30, to obtain 200 mg of 2-furoyl-9,9′-spirobifluorene(C30H1802; MW=528.57; yields of 31%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.44-8.08 (18 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 181.68 (C═O), 152.29, 149.70,149.02, 148.25, 146.78, 146.23, 140.50, 136.67 (all quaternary carbons),129.98, 129.23, 128.28, 125.02, 124.16, 121.10, 120.18, 119.88, 112.04(all CH), 65.92 (C-spiro).

IR (CCl₄, cm⁻¹): 1650 (C═O).

Example 6 Preparation of 2-(p-fluoro)-benzoyl-9,9′-spirobifluorene

301 mg of 4-(fluoro)benzoyl chloride (1.90 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with274 mg of anhydrous AlCl₃ (2.05 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CH₂Cl₂ 70:30, to obtain 460 mg of2-(p-fluoro)-benzoyl-9,9′-spirobifluorene (C32H19FO; MW=438.51; yields83%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.60-8.00 (19 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 194.56 (C═O), 167.69 (C—F), 162.65(C—F), 150.01, 149.20, 147.79, 146.09, 141.87, 140.39, 136.71 (allquaternary carbons of SBF), 134.03 (C—C═O of Ph), 132.49, 132.31,130.46, 129.16 (all CH of SBF), 127.99, 127.89 (CH of Ph, β □□∇=□),125.69, 124.30, 123.88, 120.88, 120.21, 119.58 (all CH of SBF), 115.45,115.02 (CH of Ph, γ □∇□=□), 65.95 (C-spiro).

IR (CCl₄, cm⁻¹): 1658 (C═O).

Example 7 Preparation of 2-(p-methoxy)-benzoyl-9,9′-spirobifluorene

323 mg of 4-(methoxy)benzoyl chloride (1.90 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with274 mg of anhydrous AlCl₃ (2.05 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed to reach room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CH₂Cl₂ 70:30, to obtain 570 mg of2-(p-methoxy)-benzoyl-9,9′-spirobifluorene (C33H2202; MW=450.54; yieldsof 80%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.84-7.86 (19 H, mc, ArH), 3.78(3H, s, OCH₃).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 194.75 (C═O), 162.90 (C—OMe),149.851, 148.89, 147.84, 145.45, 141.77, 140.48, 137.44 (all quaternarycarbons), 132.22, 130.28, 130.21, 128.87, 127.85, 127.80, 125.51,124.15, 123.83, 120.72, 120.09, 119.41, 113.33 (all CH), 65.89(C-spiro), 55.28 (C—OCH₃).

IR (CCl₄, cm⁻¹): 1653 (C═O).

Example 8 Preparation of 2-(pentafluoro)-benzoyl-9,9′-spirobifluorene

473 mg of pentafluorobenzoyl chloride (1.90 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with274 mg of anhydrous AlCl₃ (2.05 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CH₂Cl₂ 70:30, to obtain 482 mg of2-(pentafluoro)-benzoyl-9,9′-spirobifluorene (C32H15F5O; MW=510.46;yields of 60%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.80-8.00 (15 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, 8 vs SiMe₄): 184.33 (C═O), 150.61, 149.98,148.71, 147.32, 141.92, 140.03, 139.75, 135.35 (all quaternary carbons),130.91, 129.91, 129.06, 128.16, 128.03, 124.95, 124.57, 124.39, 123.93,121.34, 120.63, 120.26, 120.15 (all CH), 65.90 (C-spiro).

IR (CCl₄, cm⁻¹): 1677 (C═O).

Example 9 Preparation of the di-benzoyl derivative SBF(COPh)₂ (mixtureof VIIIa and VIIIb)

20 ml of dichloromethane and 0.98 g of benzoyl chloride (6.95 mmol) areplaced in a 250 ml Pyrex vessel under stirring. The mixture is cooled to15° C., then 0.93 g of finely powdered anhydrous AlCl₃ (6.95 mmol) areadded. Subsequently 1.0 g of 9,9′-spirobifluorene (I) (3.16 mmol)dissolved in 20 ml of dichloromethane are added drop wise under stirringduring 30 minutes. The reaction mixture is heated to room temperatureand then refluxed for 2 hours. 50 ml of water and ice followed by 20 mlof a 2N solution of HCl are added to the residue. The water phase isextracted with CH₂Cl₂ (3×20 ml). The combined organic phases are treatedwith 20 ml of a saturated solution of Na₂CO₃, washed with water (20 ml),dried and concentrated until obtaining 2.1 g of solid residue. Theproducts are purified by means of silica gel chromatography with eluanthexane: CH₂Cl₂ 60:40 to give two fractions. In the first fraction, 0.86g (52%) of 2,2′-dibenzoyl-9,9′-spirobifluorene (mixture of VIIIa andVIIIb) are obtained as a vitreous liquid which eventually solidifiesinto a waxy solid, and in the second fraction 0.46 g (35%) of2-benzoyl-9,9′-spirobifluorene (VII), melting point 260-261° C., areobtained.

2,2′-dibenzoyl-9,9′-spirobifluorene (mixture of VIIIa and VIIIb)(C39H24O2):

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 8.00-6.75 (24 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 195.80 (C═O), 149.82, 149.02,147.69, 145.89, 141.72, 140.27, 137.68, 136.60 (all quaternary carbons);131.94, 130.68, 130.33, 130.38, 129.80, 129.68, 128.99, 128.81, 128.71,128.14, 128.02, 127.95, 127.77, 127.11, 126.78, 125.58, 124.13, 123.76,120.78, 120.07, 119.38 (all CH), 65.82 (C-spiro): ESI-MS: (positivemode): 526.6 (M +2H⁺)

IR: (CCl₄, cm⁻¹): 1657 (C═O).

Example 10 Preparation of2,2′-di-(pentafluoro)-benzoyl-9,9′-spirobifluorene

870 mg of pentafluorobenzoyl chloride (3.48 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with695 mg of anhydrous AlCl₃ (5.21 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CH₂Cl₂ 70:30, to obtain 760 mg of2,2′-di-(pentafluoro)-benzoyl-9,9′-spirobifluorene (C39H14F10O2;MW=704.53; yields of 69%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.80-8.00 (14 H, mc, ArH)

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 184.31 (C═O), 149.01, 148.70,148.57, 139.86, 135.44 (all quaternary carbons), 131.43, 130.11, 128.60,124.64, 124.26, 121.63, 120.45 (all CH), 65.68 (C-spiro).

IR (CCl₄, cm⁻¹): 1674 (C═O).

Example 11 Preparation of 2,2′-di-(2-thienoyl)-9,9′-spirobifluorene

510 mg of thiophene 2-carbonyl chloride (3.48 mmol) are dissolved in 20ml of dichloromethane, cooling to 15° C. under stirring, then added with695 mg of anhydrous AlCl₃ (5.21 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CHCl₃ 80:20, to obtain 800 mg of2,2′-di-(2-thienoyl)-9,9′-spirobifluorene (C35H20S2O2; MW=536.67; yieldsof 94%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 7.93 (4 H, s); 7.89 (2H, s); 7.58(2H, s); 7.42 (4H, mc); 7.27 (2H, d); 7.15 (2H, d); 7.01 (2H, t); 6.75(2 H, d).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 187.31 (C═O), 148.89, 148.25,145.91, 143.59, 140.49, 137.45 (all quaternary carbons), 134.35, 133.83,129.81, 129.17, 128.27, 127.77, 124.90, 124.15, 121.04, 119.90 (all CH),65.89 (C-spiro).

IR (CCl₄, cm⁻¹): 1680 (C═O).

Example 12 Preparation of2,2′-di-(p-fluoro-benzoyl)-9,9′-spirobifluorene

551 mg of 4-(fluoro)benzoyl chloride (3.48 mmol) are dissolved in 20 mlof dichloromethane, cooling to 15° C. under stirring, then added with695 mg of anhydrous AlCl₃ (5.21 mmol) finely powdered.

Afterwards 0.5 g of 9,9′-spirobifluorene (1.58 mmol) dissolved in 10 mlof dichloromethane are added drop wise under stirring in a period of 10minutes.

The reaction mixture is allowed reaching room temperature (RT) thenheated, refluxing for 1 hour.

The solvent is evaporated off under vacuum and the residue is added with50 g of ice and 25 ml of a solution 2N of HCl.

The aqueous phase is extracted with CH₂Cl₂ (3×15 ml).

The combined organic phases are washed with a saturated solution ofNaHCO₃ (20 ml), water (20 ml), dried and concentrated to obtain a solidresidue.

The product is purified by silica chromatography with eluant hexane:CHCl₃ 80:20, to obtain 700 mg of2,2′-di-(p-fluoro-benzoyl)-9,9′-spirobifluorene (C39H22F2O2; MW=560.61;yields of 79%).

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 6.60-7.90 (22 H, mc, ArH).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 194.45 (C═O), 167.71 (C -F), 162.67(C—F), 149.02, 148.40, 146.19, 140.47, 136.84 (all quaternary carbons ofSBF), 134.06, 134.00 (all {overscore (C)} □□□□of Ph), 132.50, 132.32(all CH of Ph, β □□□=□), 130.87, 129.30, 128.35, 125.45, 124.17, 121.18,119.74 (all CH of SBF), 115.50, 115.07 (all CH of Ph, γ □□□=□), 65.91(C-spiro).

IR (CCl₄, cm⁻¹): 1659 (C═O).

Example 13 Preparation of the tert-butyl-benzoyl derivatives:2-SBF-(CO-p-tert-BuPh) (IX) and 2,2′-SBF-(CO-p-tert-BuPh)₂ (Mixture ofXa and Xb)

20 ml of dichloromethane and 1.37 g of 4-tert-butyl-benzoyl chloride(6.95 mmol) are placed in a 250 ml Pyrex vessel under stirring. Themixture is cooled to 15° C., then 0.93 g of very finely powderedanhydrous AlCl₃ (6.95 mmol) are added. Subsequently 1.0 g of9,9′-spirobifluorene (I) (3.16 mmol) dissolved in 10 ml ofdichloromethane are added drop wise under stirring for 30 minutes.

The reaction mixture is brought to room temperature and is then refluxedfor two hours.

50 ml of water and ice followed by 20 ml of a 2N solution of HCl areadded to the residue. The water phase is extracted with CH₂Cl₂ (3×20ml). The combined organic phases are treated with 20 ml of a saturatedsolution of Na₂CO₃, washed with water (20 ml), dried and concentrateduntil obtaining 2.7 g of solid residue. The products are purified bymeans of silica gel chromatography with eluant hexane: CH₂Cl₂ 60:40 togive two fractions. In the first fraction 0.39 g (26.2%) of2-(4-tert-butyl-benzoyl) 9,9′-spirobifluorene (IX), m.p. 189-191° C.,are obtained and in the second fraction 1.15 g (56.8%) ofdi-(4-tert-butyl)-benzoyl-9,9′-spirobifluorene (mixture of VIIIa andVIIIb), m.p. 100-105° C. (deliq) are obtained.

2-(4-tert-butyl)-benzoyl-9,9′-spirobifluorene (IX) (C36H28O):

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 8.0-6.7 (19H, m, ArH), 1.37 (9H, s,3×CH₃).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 195.67 (C═O), 155.70, 149.98,149.00, 147.84, 145.74, 141.81, 140.42, 137.13, 135.03, (all quaternarycarbons); 130.66, 130.01, 129.86, 128.95, 127.86, 127.82, 125.58,125.00, 124.18, 123.86, 120.76, 120.10, 119.32 (all CH); 65.95(C-spiro); 34.09 (C(Me)₃), 31.08 (CH₃); ESI-MS (negative mode): 475.9(M−H⁺).

IR (CCl₄, cm⁻¹): 1660 (C═O).

2,2′-di-(4-tert-butyl)-benzoyl-9,9′-spirobifluorene (mixture of VIIIaand VIIIb) (C47H40O2):

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄): 8.00-6.75 (22H, m, ArH), 1.34 (18H, s, 6×CH₃).

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 195.60 (C═O), 155.81, 149.01,148.22, 145.89, 140.51, 137.13, 135.01 (all quaternary carbons); 130.95,129.85, 129.06, 128.11, 125.38, 125.04, 124.10, 121.00, 119.49 (all CH);65.72 (C-spiro), 34.09 (C(Me)₃), 31.03 (CH₃).

ESI-MS (negative mode): 655.6 (M+H₂O);

IR (CCl₄, cm⁻¹): 1660 (C═O).

Example 14 Preparation of a Mixture of Xa and Xb: Alternative Method

a) Preparation of 2,2′-diacetyl-9,9′-spirobifluorene

2.95 g of finely divided anhydrous AlCl₃ (22.12 mmol) are added to 1.0 gof 9,9′-spirobifluorene (3.16 mmol) dissolved in 20 ml of carbonsulphide. 0.5 g of CH₃COCl (6.32 mmol) are added to 20 ml of carbonsulphide drop wise under stirring for 10′. The mixture is then refluxedduring one hour and dried in a Rotavapor. It is decomposed with 50 g ofice and 25 ml of HCl 2N and the organic phase is extracted withdichloromethane; the organic extracts are recombined, washed with waterand dried on anhydrous sodium sulphate.

Purification is performed by means of liquid chromatography, using aCH₂Cl₂ hexane 40:60 mixture as eluant to give 1.01 g of2,2′-diacetyl-9,9′-spirobifluorene (C29H20O2; MW=400.48; yield 80%)(m.p.=255-257° C.).

b) Preparation of the 2,2′-dicarboxylic acid of the spirobifluorene.

0.6 ml of bromine (11.68 mmol) and then 0.75 g of2,2′-diacetyl-9,9′-spirobifluorene prepared as above (1.88 mmol) and afew drops of THF (tetrahydrofuran) are added drop wise under stirring toa solution of NaOH (1.5 g in 20 ml of water) at 0° C. After refluxing,the solution is stirred for 4 hours; the pale yellow solution is thentreated with a saturated solution of Na₂S₂O₃ until the colourdisappears. After acidification with diluted HCl (3 N), the THF iseliminated via the Rotavapor and the water phase is extracted withCH₂Cl₂ several times; the combined extracts are washed in water and leftto dry on anhydrous sodium sulphate. After column purification (eluantAcOEt:CHCl₃=10%), 420 mg of the 2,2′-dicarboxylic acid of thespirobifluorene (C27H16O4; MW=404.43; yield 55%) are obtained in theform of clear prisms like water, m.p. 352° C.

1H-NMR (CDCl₃, 200 MHz, δ vs SiMe₄) 6.61-7.81 (14H, m, Ar-H)

13C-NMR (CDCl₃, 50 MHz, δ vs SiMe₄): 206.63 (C═O); 167.09, 149.78,149.17, 147.24, 141.58 (all quaternary carbons); 130.91, 130.17, 129.35,125.61, 124.75, 122.30, 121.30 (all CH); 66.52 (C-spiro)

c) Preparation of the 9,9′-spirobifluorene 2,2′-dicarbonyl dichloride

3 drops of DMF are added to a solution containing 2 g of SBF(COOH)₂prepared as above (5 mmol) in 20 ml of SOCl₂ (275 mmol) and the mixtureis refluxed for 4 hours. After cooling, the excess thionyl chloride isremoved under reduced pressure; petroleum ether (30-50° C.) is added anddistillation is performed in a vacuum to obtain the raw acid chlorideSBF(COCl)₂ (C27H14Cl2O2; MW=441.32; yield: ca 60%).

d) Preparation of the2,2′-di-(4-tert-butyl)-benzoyl-9,9′-spirobifluorene

0.66 g of finely powdered anhydrous AlCl₃ (MW=133.3, 4.98 mmol) at 15°C. (water-ice bath) are added to 1 g of SBF(COCl)₂ prepared as above(MW=441.32; 2.27 mmol) in 20 ml of dichloromethane. 0.77 ml oftert-butylbenzene (MW=316.4, 4.98 mmol) are added drop wise understirring for half an hour and the mixture is left to reach RT. It isthen refluxed and stirring is continued for a further two hours. Themixture is decomposed with water and ice, then treated with diluted HCland the organic phase extracted with dichloromethane.

The organic extracts are re-combined, treated with sodium carbonate,washed with water and dried on anhydrous sodium sulphate. This isfollowed by column chromatography using a mixture of 40%dicloromethane-hexane as eluant, to obtain the2,2′-di-(4-tert-butyl)-benzoyl-9,9′-spirobifluorene. TABLE 1 Standardpotential for mono derivatives Products E° (V vs SCE)2-(4-nitrobenzoyl)-9,9′-spirobifluorene −0.812-(pentafluoro)-benzoyl-9,9′-spirobifluorene −1.362-(2-furoyl)-9,9′-spirobifluorene −1.492-(4-fluorobenzoyl)-9,9′-spirobifluorene −1.602-benzoyl-9,9′-spirobifluorene −1.622-(4-methoxybenzoyl)-9,9′-spirobifluorene −1.642-(4-tert-buthylbenzoyl)-9,9′-spirobifluorene −1.69

TABLE 2 Standard potential for di-derivatives Products E° (V vs SCE)2,2′-di-(pentafluoro)-benzoyl-9,9′-spirobifluorene −1.392,2′-di-(2-thienoyl)-9,9′-spirobifluorene −1.472,2′-di-(4-fluorobenzoyl)-9,9′-spirobifluorene −1.572,2′-di-(4-tert-buthylbenzoyl)-9,9′-spirobifluorene −1.632,2′-dibenzoyl-9,9′-spirobifluorene −1.65

In the above tables 1 and 2 there are shown the values of E°corresponding to the compounds prepared, calculated vs. SCE according tothe following procedure. The apparatus used for the determination of thestandard potentials of the described compounds was the AMEL System 5000.

The electrochemical technique used for the determination of the standardpotentials of the described compounds was Cyclic Voltammetry.

The solvent system was tetraethylammonium perchlorate in acetonitrile0.1 M; the cathode was a glassy carbon electrode; the anode was aplatinum wire; the reference electrode was a saturated calomelelectrode; the concentration of the substrate was 0.001 M; the sweeprate was 0.2 V/s.

The standard potentials (E°) of the described compounds were obtainedfrom the formula: E°=(E_(pc)+E_(pa))/2 were E_(pc) and E_(pa) representrespectively, the cathodic peak potential and the anodic peak potentialfor the first reversible reduction process.

The standard potentials (E°) indicated for2,2′-di-(4-fluorobenzoyl)9,9′-spirobifluorene and2,2′-di-(pentafluoro)-benzoyl-9,9′-spirobifluorene were obtainedsubtracting 30 mV to the corresponding E_(pc) values once extrapolatedat sweep rate=0 V/s

Example 15 General Procedure for the Synthesis of Radical Anions

The aprotic solvent, typically N,N-dimethylformamide, acetonitrile, ortetrahydrofuran, is dried according to usual procedures. An amount ofsupporting electrolyte, typically tetraethylammonium perchlorate,tetrabutylammonium tetrafluoroborate or lithium perchlorate, is driedaccording to usual procedures and added to the solvent in order to givea 0.1 M solution.

The chosen compound is added to the electrolytic solution in thecathodic section of a divided cell, under nitrogen flux, to give aconcentration between 0.1 M and 0.1 mM, preferable between 0.01 M and0.5 mM and particularly preferable 1 mM. In the cathodic section of thecell are placed a reticulated vitreous carbon (RVC) electrode as thecathode and a calomel electrode as the reference electrode. In theanodic section of the cell, divided from the cathodic section by agelled electrolytic solution, a platinum gauze electrode, as the anode,is placed. A d.d.p. 0.2 V more negative than the standard potential E°(vs SCE) is applied.

Example 16 Synthesis of the Radical Anion of the Compound (Mixture of Xaand Xb)

Alumina (Riedel De Haen) pre-treated to 600° C. for 12 h to make itanhydrous is added to a portion of N,N-dimethylformamide (DMF) (RiedelDe Haen). The DMF is then distilled twice under reduced pressure at atemperature not exceeding 27° C. A quantity of tetraethylammoniumperchlorate Et₄NClO₄ (Fluka), previously dried at room temperature undervacuum for 24 h, is added to DMF so as to form a solution withconcentration 0.1 M. The9,9′-spirobifluorene-2,2′-di-(4-tert-butyl)-benzoyl (mixture of VIa andVIb) is added under nitrogen flux to the electrolytic solution in thecathodic compartment of a divided electrolytic cell in order to obtain aconcentration 0.001 M. A cross-linked vitreous carbon electrode and thesaturated calomel reference electrode (SCE) are placed in the cathodiccompartment of the cell divided into two compartments. In the anodiccompartment, separated from the cathodic compartment by theappropriately gelled electrolytic solution, a solution of 20 ml ofN,N-dimethylformamide (DMF) (Riedel De Haen) containing 5 g oftetraethylammonium perchlorate Et₄NClO₄ (Fluka) is brought to boilingpoint, then 1 g of methylcellulose (BDH Chemicals) is added very slowly;boiling is maintained for approximately 5 minutes with stirring, then,while hot, the gelled solution is poured into the anodic compartmentcontaining the Pt network anode. A d.d.p. of −1.6 V (vs. SCE) is appliedbetween the electrodes.

REFERENCES

-   1. Haas G. and Prelog V., Helv. Chim. Acta (1969) 52, pp. 1202-1218.-   2. Aviram A., J. Am. Chem. Soc. (1988) 110, pp. 5687-92.-   3. “Molecular Electronics: science and technology” Aviram A. and    Ratner M. editors, Annals of the New York Academy of Science,    Vol.1852 (1998)-   4. Gore P. H., Chem. Rev. (1955), 55, pp. 229-271.-   5. “Organic Electrochemistry”, Lund H. and Hammerich O. Eds., Marcel    Dekker Inc, NY, 4^(a) Ed., (2001).-   6. “Electrochemical methods”, Bard A. J. and Faulkner L. R., Wiley,    N.Y. II ed. (2001), p. 3.-   7. Laquindanum J. G., Katz H. E., Dodabalapur A. and Lovinger A.    J., J. Am. Chem. Soc., (1996) 118, pp. 11331-11332.

1. Spirobifluorene (“SBF”) derivatives and corresponding radical anionshaving the following general formula (II):

in which K, L, M and N, the same or different from each other, areindependently: H or A-C═O, with the proviso that it is never K=L=M=N═H,wherein A is an aromatic group bearing at least one radical R, with R═Hor aliphatic group.
 2. Spirobifluorene derivatives and correspondingradical anions according to claim 1 wherein A is selected among:aromatic groups, aromatic groups containing heteroatoms, condensedaromatic groups, condensed aromatic groups containing heteroatoms, andcorresponding derivatives.
 3. Spirobifluorene derivatives andcorresponding radical anions according to claim 1 wherein A is selectedin the group of the following derivatives: phenyl, biphenyl, 1-naphthyl,2-naphthyl, 2-thienyl, 2-furyl, 2-pyrrolyl, 3-thienyl, 3-furyl,3-pyrrolyl, 9-anthryl, biphenylenyl, perylenyl, fullerenyl, andcorresponding derivatives.
 4. Spirobifluorene derivatives andcorresponding radical anions according to claim 1 wherein R=linear,branched or cyclic aliphatic C₁-C_(n), with n positive integer≧0. 5.Spirobifluorene derivatives and corresponding radical anions accordingto claim 1 wherein A is substituted with at least one R′ group where R′is selected in the group of: halogens, trifluoromethyl, hydroxyl, —SH,—SC[C₁₋₆(alkyl)], alkoxy, nitro, cyano, —COOH. —COOC[C₁₋₄(alkyl)], —NH₂,—NC[C₁₋₄(alkyl)]₂, benzyl, or benzoyl.
 6. Spirobifluorene derivativeshaving the general formula (III) and corresponding radical anions:

wherein A is an aromatic group and R₁═R₂═R₃═H; or R₁═R₃═H andR₂═C₁₋₆(alkyl); or R₁═R₂═H and R₃═C₁₋₆(alkyl); or R₂═H andR₁═R₃═C₁₋₆(alkyl).
 7. Spirobifluorene derivatives having the generalformula (IV) and corresponding radical anions:

wherein R₅=A-C═O with A=aromatic group and R₄═R₆═H; or R₅=A-C═O andR₄═R₆═C₁₋₄(alkyl); or R₆=A-C═O and R₄═R₅═H; or R₆=A-C═O andR₄═R₅═C₁₋₄(alkyl).
 8. Spirobifluorene derivatives having the generalformula (V) and corresponding radical anions:

wherein R₇═R₉=A-C═O with A=aromatic group and R₈═H; or R₇═R₉=A-C═O andR₈═C₁₋₄(alkyl).
 9. Spirobifluorene derivatives having the generalformula (VI) and corresponding radical anions;

wherein R₁₀═R₁₂═R₁₂=A-C═O with A=aromatic group.
 10. Spirobifluorenederivatives and corresponding radical anions according to claim 6wherein A is selected among: aromatic groups, aromatic groups containingheteroatoms, condensed aromatic groups, condensed aromatic groupscontaining heteroatoms, and corresponding derivatives. 11.Spirobifluorene derivatives and corresponding radical anions accordingto claim 6 wherein A is selected in the group of: phenyl, biphenyl,1-naphthyl, 2-naphthyl, 2-thienyl, 2-furyl, 2-pyrrolyl, 3-thienyl,3-furyl, 3-pyrrolyl, 9-anthryl, biphenylenyl, perylenyl, fullerenyl, andcorresponding derivatives.
 12. Spirobifluorene derivatives andcorresponding radical anions according to claim 1 wherein L=M=N═H andK=A-C═O in position 2, with A=phenyl and R═H.
 13. Spirobifluorenederivatives and corresponding radical anions according to claim 1wherein L=N═H, K and M in position 2 and 2′ are A-C═O, with A=phenyl andR═H.
 14. Spirobifluorene derivatives and corresponding radical anionsaccording to claim 1 wherein L=N═H, K and M in position 2 and 7′ areA-C═O, with A=phenyl and R═H.
 15. Spirobifluorene derivatives andcorresponding radical anions according to claim 1 wherein L=M=N═H, K inposition 2 is A-C═O with A=phenyl and R=p-tert-Bu.
 16. Spirobifluorenederivatives and corresponding anionic radicals according to claim 1wherein is: L=N═H, K and M in position 2 and 2′ are A-C═O, with A=phenyland R=p-tert-Bu.
 17. Spirobifluorene derivatives and correspondingradical anions according to claim 1 wherein is: L=M=H, K and N inposition 2 and 7′ are A-C═O, with A=phenyl and R=p-tert-Bu. 18.Spirobifluorene derivatives and corresponding radical anions accordingto claim 1 in a mixture of them as enantiomers.
 19. Spirobifluorenederivatives and corresponding radical anions according to claim 1 inoptically pure form.
 20. Method for preparing the Spirobifluorenederivatives according to claim 1 comprising the following steps: use thenon-functionalised SBF as the starting product (formula (I)) and add toit the compound A-C═OCl with A=aromatic group, in the presence of aLewis acid, in a solvent at a reaction temperature from 10° C. toreflux.
 21. Method for preparing the Spirobifluorene derivativesaccording to claim 1 comprising the use, as intermediate, of SBFfunctionalised as acid chloride SBF(COCl)_(x), with x positive integer≧1and equal to the number of substituents to be obtained on the SBF; saidacid chloride is then combined with A-H, in which A=aromatic group, saidacid chloride intermediate being prepared from the correspondingcarboxylic acids of the SBF, SBF(COOH)_(x), in turn obtained from thecorresponding acetyl derivatives SBF(COCH₃)_(x), x having in both casesthe above-mentioned meaning. 22-24. (canceled)
 25. Electrochemicalmethod for preparing the radical anions corresponding to the derivativesof the SBF according to claim 1, said method being characterised in thatsaid derivatives, to be transformed into radical anions, at aconcentration between 0.1 M and 0.1 mM, are added to an anhydrousaprotic solvent containing a supporting electrolyte, also anhydrous, inorder to obtain a concentration of the latter of between 1 M and 0.01 M,the mixture then being placed in an electrolysis cell and a d.d.p.applied between the electrodes in order to obtain the required radicalanion.
 26. Electronic devices, comprising elements provided on theirsurface with at least one layer of a film or coating comprising at leastone of the compounds according to claim
 1. 27. (canceled)
 28. Systemsfor electroluminescence, molecular-based computational systems, OLEDs,molecular switching components, components for non-linear optics,molecular-based computational systems, field-effect transistors,semiconductors with negative differential resistance, said systemscomprising elements provided on their surface with at least one layer ofa film or coating comprising at least one of the compounds according toclaim
 1. 29. 9,9′-Spirobi[9H-fluorene]-2,-carbonyl chloride,9,9′-Spirobi[9H-fluorene]-2,2′,7-tricarbonyl trichloride or9,9′-Spirobi[9H-fluorene]-2,2′,7-7′-tetracarbonyl tetrachloride.